Fluid pressure brake



C. C. FARMER FLUID PRESSURE BRAKE Filed Deo.

July 2.8, l931. v

Patented July 28, 1931 .enYnjEev FARMER, oF I1?;misRuRerH,.'RENNSYRVRNIA, issIGNpRmoinlin .,WEST'IRG- HOUSE 1R-BRAKE ,ooMPRRi ionWILMERDING, .PENNSYRVANIR A lcoRRoRn- Ryman ,RRnssURE BRAKEppliatign'led neeeniberl, g19,75%). .Serial No. 417,651.

' g'lheiriple valve device `l may enjipiiee a easingehaving .arpistonehzimber `Yfrhleh isfcenneetedlto the brake pipe'2,thr0`u'gh'aJpipe and passage 10, ,and rcontains ai pistn ,having st'einglQ adaptedv.tdr'epeiafe Ia .mein Slide .valve 1,3 .and ,M1 ,aimeliy de X'izllife'lContained in ateliarnbei' 155' Whih yChmfiber iS connected totheauniliary peserx l y 4Veil1 8 through a passage 116v. 'i`'eqntrfglvreyeeifvei lendv auxiliary reeervglr are The @wel lvedfvcvmay 'ya easing having e' vel tuiningfaelicle.valve v1 8 f'eenineetedtoxa `stein 1 9; The Valve llSnnd steinli) are adapted' to be.'operat'ed' tspaeflexible. imprime-msm 21. pidan@- 'quiredin' theczisving. 'y y* 4 Chamber lf?7 and i Yfollower meinbei een# t'iinechinnehziinber 25, ivhiehiehembei" constantly egnneeted to theA:itinfosphelfe thivoug'hja paesage `2 6. The melinberilfhgis'sereW-thre'zidei Connection with Vthe stem' l1,9 end the upper end ofseideienibe engages theunfdei lswidefoi the diephregni "Continued yin avehember' 27 at one eide ef ythe diaphragm 2O is'faniovableA stop 28,euhthe ,pressure ef@ Spring 29. The flexible @nphi'agm 22 ,iserianipeghbeytw'ei-n e. 'fgiiowelfpiate 30', epntfaineglin ltheQliffunbel A1,7.@11fh1` tained in a ehaniber thiiouglithe.inediuin l unutigS-heving Scieivthregtdegl'KConnection @with the lQWel @nd ,.Of ,theStem 19,

Whfii @11d .passeethrough the .follewr .plate and thediztphrngm, theLupper side of the plete 3,0 abutting against e vshoulder 34 Af0rn1ef`i.o nthe stem 19. .Containedfin 4Athe .chamber 52. :and nteijiosedbetufeenfthefplate nSlendtl'ie Casing is e cpl sprjug'-S, the upper endof,the'springvseaiting againstthe under Side offtliepla'te. r

`--ifVtlfiin-th'e chanibehgthe lower end of between the lower end of themember and the casing.

The member 36 is provided with a longitudinal groovel39, the lower endof which opensV into a circular' groove 40 formed in the member adjacentits lower end, said grooves establishingV communication *fromVthechamber 38 to thechamber 32,.

Integral with the casing, and contained in the chamber 17, is a lug 41,which, at its end, is provided with a seat for the` slide valve 18. I

The combined charging and discharging valve device 6 may comprise acasing in which there is secured a flexible diaphragm 42, having securedvthereto a stem 43 adapted to operate aslidevalve 44 contained in achamber 45 at one side of the diaphragm.

VContained in a chamber 46 atrthe other side of the diaphragm 42, is a'stop 47 which is subject to the pressure of a coil spring 48 and whichis adapted to be engaged by yone end of a stem 43. l

The control reservoir 5 is constantly connected to the valve chamber 45in the valve device. 6 through a pipe and passage 49, and also to thediaphragm chamber 27 in the control valve device 4 through valve chamber45 and a passage 50. Y

It will be understood that the triple valve device 1 andthe controlvalvedevice 2 here- 4inbefore described in detail, are identical inconstruction with the corresponding devices of the equipment shown anddescribed in detail in my aforementioned pending application, and thesedevices function to control the brakes in identically the same manner asdescribed in this pending application, and'since the details of thevalve device 6 and its operation to charge and discharge fluid underpressure to and from the control reservoir is all that materiallydiffers from the corresponding charging valve of the pendingapplication, the following clescription will be limited to the operationof the tripleV valve device 1 and control valve device 4 insofar as theycooperate with the vvalve device 6. l

In initially charging the equipment, fluid under pressure supplied tothe brake pipe 2 flows to the piston chamber 9 in the triple valvedevice 1 through the pipe and passage 10, causing the piston 11 to bemoved to its innermost or release position, as shown in Fig. 1 of thedrawing, carrying with it the slide valves 13 and 14. Vlithy the pis'-ton in this position, liuid Vsupplied to the piston chamber 9 flows tothe valve chamber 15 in the triple valve device and auxiliary reservoir3 through apassage 5l, chamber 38 in the control valve device, grooves40 and 39 in the member 36, diaphragm chamber 32 and passage 16.

Fluid under pressure from the brake pipe 2 is also supplied'to thediphragm chamber 46 in the charging Vvalve device 6 through the pipe andpassage 10, and the pressure of fluid thus supplied to this chamber, andactingl on `one side of the diaphragm 42, causes said diaphragm todeflect and shift the stem 43 and slide valve 44 toward the Vright handto their charging position, in

which the slide valve uncovers a port '52, so that fluid Yunderpressure, supplied to the passage 16, will also flow to the controlreservoir 5 past a ball check valve 53, through port 52, valve chamber45v in the chargingvalve device 6 and passage and pipe 49. From thevalve chamber 45, fluid kunder pressure also flows to the diaphragmchamber 27 in the control valve device 4 through the passage 50.

The flexible diaphragms 20 and 22 are of equal area, and since vthepressure -of fluid supplied to the diaphragm .chambers 27 and 32 aresubstantially equal, the pressure of the spring 35 will maintain thediaphragm 2O in engagement with the stop 28. When the diaphragm engagesthe stop 28, a passage54through the lug 41 is uncovered by the slidevalve 18, thus maintaining come munication open from thevalve chamber 17to the atmosphere through passage 54, a

port 55 in the valve plug 56 of the release changeover valve device 8and `restricted atmospheric passage'57, when said plug valve is ingraduated release position vas shown in Fig. 1..

lVith the triple valve device in release position, the brake cylinder 7is connected to the valve chamber 17 ofthe control valve device througha pipe and passage 58a cavity 59 in the triple valve slide valve 13,

and a passage 60 thus venting the brake` cylinder to the atmosphere.

lVith the valve device 6 in its charging position, a reduction vchamberor reservoir 61 is connected to the atmosphere through a pipe andkpassage 62, a cavity 63 in the slide valve 44 and a passage 64. Y

With the equipment thus fully charged and the brake cylinder 7 connectedwith the atmosphere, a service application of the brakes is effected' bymaking a .Y gradual brake pipe reduction in the usual manner, whichresults in a corresponding reduction in the pressure of fluid in thepiston chamber 9 of the triple valve device 1. Y`When the pressure ofAfluid in the piston chamber `9 is reduced,the pressure of fluid in theslide valve chamber 15 causes the triple valve piston 11 to operate toshift the auxiliary slide valve 14 and main vslide valve 13 totheirapplication position.

-When the triple valve slide valves have thus been operated to theirapplication positions, fluid under pressure `supplied to the triplevalve chamber lvfrom the auxiliary reservoir 3, flows to the brakecylinder 7 Leoy ' y valve device and to the auxiliary reservoir fthetriple valvey slide lvalve control valve chamber .-17,

duction, the control :reservoir pressure, present' in chamber`27 andacting'on ,the diaphragm 20, causes the slide'va'lve 18 to beshii'fteddownwardly against fthe reduced auxiliaryreservoir pressure chamber 32and'tliepressure ofthe spring 3 5, lapping .thevppassage elandtherebyclosing cominunioation from the chamber 17 ,to the atmosphere. l

,The spring 18 ofthe valve device 6 may befefsuch L a valuethat whenthebralre lpipe is vcoinpletely 4vented and thecontr'ol reservoir hasbeen reduced to, say; pounds, the pressure of the. spring will operatethe dia- Y to shift/,theslide valve 44 to .blank the .exhaust passage'62thus prevent ingthecontwl reservoiripressure from being` reducedbelowthe equalization pressure of fthe vauxiliary reservoir and brakecylinder. fltiyvillfthusbe seenthat l*when a service reduction in brakepipe v,pressure is effected, A the.valveClQYC 6 willnotoperate to causeafreductionin control reservoir pressure. To release the'brakes after aservice ap-y ;plicatiomlthe pressure of Huid in thebrake 'pipe l2 isincreasedin the'fusual vmanner,

causing the Itriple A'valve piston 11;to', operate tdrelease` position,inwhich the .passage y5l is againconnected tov the pistonfchan'iber y9,so`;tliat fluid r at brake pipe pressure again rsupplied from pistonchamber 9 to the diaphragm .chamber 32 yin the control 3. I Now when thepressure of fluidthussupplied tor the ydiaphragm chamber is againsubstantially equal .to the control reservoir pressure in thediaphragmchainber 27, the s pressure ,of the spring '3 5 causes thediaphrag'into shift thestem 1,9; and slide ,valve 11,8 upwardly luntilthe ,diaphragm 2O enthe inner surface rof thefstop 2 8, l at fvvhichItime the operation of the control ,valve device will cease and theslide valigie 18 will uncover thefpassage 51. 1.

` y ,'llhe operation oftheltriple,valvepiston11 torelease position,shifts the triple valve slide valves 13 and 14 to their releaseposition, inwhich fluid -under pressure from the brake cylinder isfventedto the atmosphere through pipe vand passage 58, cavity 59 in ,13,passaeer), past the krend ofthe control slide Yvalve 18, throughkpassage 5 4, porty55 in the change-over valvey def vice 8 L,andIpassage A,57.

QInorderV- to control Ia train on a grade,

itiisth kpractice ftepaltereately errlf eetl Theiirst application of thebra-kes, with trainen the descending grade, willbe the effected .insubstantially the same manner as has hereinbeforebeen` describedinconnection withK a service application ofthe brakes.

Thebrale pipe is now recharged to the norinal pressure, causingthetriplevalveldevice to operate to release position, in ,which Huid underpressure in the jbrakecylinder .7y will How to the atmosphere tthe same`manner as before described. pressure o1c iiuid in ,the chamber ,17 Iis4reduced Vsufi'ciently thaty the .upward ,pressure on the ,under side ofE large diaphragm 21, as well as the upward lpressureoj,Huid

inchamber'32lon the diaphragm less than the downward pressure of Vfluidl in vthe chamber 27 on the upper side of the diaphragm 20, andthedownward pressure fluid on the diaphragm22, the controlvalve devicewillbe causedto operate dovvnwardly, shiftingthe slidevalve 18 tok.aposition in which itflaps the passage 5,4thusclosing communicationfrornthe chamber 17 to the/atmosphere and ,retaining a predeterminedpressure inthe bralecylinder which isproportienate to the overcharge ofthe equipment, which overcharge is governedgby'tlle @ngineeiaccordingtothe condition of the grade. Nowppon'effecting are-application of thebrakes, ythe brake cylinder pressure obtained will exceed that retainedlin the brake v cylinders i from the Vprevious application, by .i111,amount .rrerolftional fto the brake pipe reduction, thereby insuringthe proper control of the train.

If, when thevfoot of the grade is reached, thev equipment is vagainrecharged ,with iiuid .at a ,pressure lequal A.to the originalovercharge,',the control valve device 4 will again operate ,to release.positionnas shown in the drawings, thus exhausting all brake cylinderpressure tothe` atmosphere. I twill thus be seen that the control ,valvedevice will `perform the :functions ofa retainer' valve device andv:that the engineer may readily. andv accurately` control its'foperationin accordance with th conditions of By maintaining .the equipmerit,over- Charger?, th, Qontrol wel@ devi@ es 'When kthe der'ed ineffectiveas a brake cylindervpressure retainer and the train may proceed with theequipment thus overcharged.

If, at the foot of the grade, the engineer desires to'render the controlvalve device ineffective as a brake cylinder' pressure retainer, andalsodesires to reduce the pressure of fluid in the equipment' to thatnormally'carried, he operate's'the usual brake valve device toapplication position to effeet an application of the brakes. Now, whenthe brake pipe pressure is reduced to a' predetermined value, say forinstance to 15 pounds, the control reservoir pressure present in thevalve chamber in the valve device 6, causes the diaphragm 42 to deflecttoward the left hand against the pressure ofthe spring pressed stop 47and the pressure of fluid in the brake pipe, operating the slide valve44 to a position in which the passage 62 is uncovered, sothat fluidunder pressure from the'control reservoir 5 will reduce into thereduction chamberv 6l.

The engineer now resets the feed valve device tosupply fluid underpressure to the brake pipe at the normal pressure, so that when theengineer operates the brake valve device to release position, theequipment will be recharged with fluid under pressure at the normalpressure. When, in thus recharging the equipment, the brake pipepressure present in the chamber 46 in the valve device 6 and acting onthediaphragm 42, becomes greater than the opposing pressure of fluid inthe valve chamber 45, the diaphragm 42 will flex toward the right hand,shifting the slide valve 44 to a position in which fluid under pressurefrom the reduction reservoir'is vented to the atmosphere by way of pipeand passage 62, cavity 63 in theslidefvalve 44 and passage 64. f Y yFrom the lforegoing description, it will be seen that I havey providedmeans whereby the control reservoir pressure may be ref-y duced withoutin any brake cylinder pressure. Y

The volume of the reduction reservoir way Vaecting the may be such'that,when the reduction reservoir and an overcharged control reservoir areconnected together, the equalized presl sures thereof may besubstantially .the same as the normal control reservoir pressure or maybe of such volume that the equaliz tion pressure may be substantiallyequal to the normal pressure of the spring 48, so tha if the spring 48should become weak or broken the reduction of control reservoir pressurewill be limited. j

In Fi 2 Vof the drawings, a modification of the invention has beenvillustrated in which the valve device 6 is operative to discharge lfluidunder pressure from the 'control reservoir to the atmosphere through apassage instead of to a reduction resera voir or chamber as is the easein the form shown in Fig. l.

While two illustrative embodiments of the invention have been describedin detail, itis not my intention to limit its scope to these embodimentsor otherwise thany bythe terms of the appended claims. K

Having now described my invention, what I claim as new and desire tosecure by Let'- ters Patent, is:

l. In a fluid pressure brake, the combination with a brake pipe and abrake cylinder, of a normally charged reservoir, valve means subject tothe pressure; ofv fluid from said reservoir for controlling the pressureof fluid in the brake cylinder, and means oper ated upon a reduction inbrake pipe pressure a predetermined amount below normal for reducing thepressure of fluid in said reservoir without increasing the pressure offluid in the brake cylinder.

2, In a fluid pressure bralethe combination with a brake pipe, anauxiliary reservoir and a brake cylinder, of a normally 'charged controlreservoir, valve means subject to the opposing pressures of fluid fromsaid control reservoir and from said auxiliary reservoir for controllingthe pressure of fluid in the brake cylinder, 'and means operated upon areduction in brake pipe pressure a predetermined `amount below normalfor reducing the pressure of fluid in said 'reservoir without increasingthe pressure of fluid in said auxiliary reservoir.

3. In a fluid pressure brake, the combination with a brake pipe and abrake cylinder, of a normally charged reservoir, valve means subject tothe pressure of fluidfrom said reservoir for controlling the pressure offluid in the brake cylinder, a reduction chamber, and means operatedupon a reduction in brake pipe pressure a predetermined amount belownormal for venting fluid under pressure from said reservoir to saidreduction chamber. Y

4. In a fluid pressure brake, the combina# tion with abrake pipe and abrake cylinder, of a normally charged reservoir, valve means subject tothe pressure of fluid from said reservoir for controlling the pressureof fluid'in the brake cylinder, a reduction chamber, and means operatedupon a reduction in brake pipe pressure a predetermined amount belownormal for lventing fluid under pressure from said reservoir to saidreduction chamber and operated upon an increase in brake pipe pressurefor venting fluid under pressure from said chamber.

5. In a uid pressure brake, the combination with a brake pipe and abrake cylinder, of a normally'charged reservoir, Vvalve means subject tothe pressure of fluid from said reservoir for controlling the pressureof fluid in the brake cylinder, a reducl tien chamber, and meansoperated upon a lso temerarios lis-16,0%

er charging said reservoir andvfor Venting fluid under pressureV fromsaidl ehamber.

` V61 In*alfluidipressurebrake, the combination With Ia brake" pipe andbrake cylinder, of'a' normally charged reseryoir valve means silbjeot tothe' pressurev of fluid from said reservoir for controllingk thepressure of fluid the brake" cylinder, yay reduction olla Jber, andmeans operated upon a reduc-V tion in brake.. pipe pressurevvpredetermined amount bellyv normal for venting fluidunder pressure'fromAsaidreservoir to said rfeduotlo4 7 elianiber an'dfoperated upon an ininlbr'ilrei'pipie` pressure above theA redueedpiressfureA Huidrin saidreservoir for rfe'iitfin'g4v fluid" under pressure from said chamber;

7L In all fluid pressure bralre5 the combina'- l n r brakepipeand abrakeV cylinder, of 'a'v nbriiall'y chargedjreservoir, valvemeanssubject to tliew'pressure of fluid' from said` reservoir forcontrolling the pressure of fluidf in the cylinder, a reductionllainber', and means' operated upon` a reduction k in brakepipep'ressure aglpredetermined amount belbuz normal for yenting fluidunder`r pressure from said reseryoir to said' re duction chamberAoperated upon an in- SQ yIna fluid pres brake, the combina# 4 crease` inbrakeV pipe pressure above the ren tiiiiwitliA a brake pipe and a' brakecylinder, 4 0

of 'a' normally 'charged' reservoir, Valve ns'subjct to, ther pressureof fluid from"l saidreserlvir for controlling the pressure of fluidA 1nthey brake cylinder, a reduction c bei,k and means operated upon a re-Vduction'in pipe pressure a predeterm ed' amount belov.T normal .forVenting' yflu l" under "pressure from said reservoirV to|` saidreduction chamber. and operated upon an in erease in brake' pipepressure for Ventfluid unf r pressure pli'ere'. f

9i InV aifiid pressur'e'br'ake, the Combination with a brake pipe and abrake cylinder,

from" said chamber' of a normally charged reservoir, Valve means subjectto the pressure of fluid from said reservoir for controlling thepressure of liuid in the brake cylinder, a reduction chamber, and meansoperated upon a reduction in brake pipe pressure a predetermined amountbelow normal for Venting fluid under pressure from said reservoir tosaid reduction chamber and operated upon an in crease in brake pipepressure for recharging said reservoir and for venting fluid under ei inbrake pipepressure ferirey f chamber, and means operateddupon'; af' reider, of' anormall'y ehargedreservoir,*Valve means subyect to thepressure ofii'uld' from said' reservoir for controlling" the pressure offluid in'` the brake cylinder, and;r mea'lsfv operated upon a reduction4in brake poe" pressure'l a predetermined amount' :bloiy normal forreducing the pressure fluid inl said reservoir, said vmeans beingvoperat'iyev topr'event theI pressure of fluid in sa'idres' ervoir frombeing reduced below a piedfermined pressure'l n l n s ll. Ina fluidpressure brake, the'A crombination Witlia brake pipe and a brake cylin`-der, of a normally charged" reservoir7 valye means subjectv to thepressure oi fluidf'r'o'm said reservoir for controllingrj the pressureof fluid in the brake cylinder,4 a reductiek duction in brake pipepressure a predeter-v mined amount below` normal for' Venting fluidunder pressure from reseri'foir said reduction chamber; said means beinj'l operative o limit the amount of fluid under pressure ventedfrom"saidlreserroirf p l2. In a fiuid pressure brakepthle combi;-d

ynation Witlra brake pipe and a br' re' cylinf.

der, of a normally charged res'erioiufvalye means subject tothe pressureoffiuid frornf said reservoir for controlling the pressure" of fluid inthe brale cylinder,` ay reducuion chamber, means operated upon areduction in brake pipe pressure a predetermined amounty below nornialfor Venting fluid un der pressure yfrom said reservoir to said Chamber,and a spring cooperating 'Witlif said means for limiting the amountVv offluid' under pressure vented from said reservoir.y

13. In a fluid' pressure brake, they combif nation with aA brake'pipe;an auxiliary res",-I ervoir and abralre cylinder, of a normally chargedVreservoir, valve means*subjecttol the opposing pressures of theauXiliaryr'esQ eryoir and s'aidV normally charged reservoir' forcontrolling the pressure of fluid in` tlr'e` brake cylinder, yareduction chamber,andl means' operated upon an overreducti'orr iiivfbrake pipe pressure for venting` under pressure from saidI normallycharged resei"' Voir to'said chamber.

ll. In a fluid pressure' brake", the combination with a Abrake pipe anda brake cylinder, of ak reservoir normally charged With 'flu-id at thenormal brake pipe pressure', means operative upon an' increase in' brakepipe pressure above'normal for' over! cliarging' 4said reservoir abovenormal; `Valve'mechanism subject to the' pressure ofV fluidv from theovercharged' reservoir for controlling therelease offluidl underprefssure from the1 vbrake* cylinder, and a reddetion chamber, saidmeansbeing operat'iy'e ifo wir

upon effecting a reduction in brake pipe pressure a predetermined amountbelow normal for venting fluid under pressure from said reservoir tosaid chamber.

In a fluid pressure brake, thevoombination with a brake pipe and a brakecylinder, ofa reservoir normally charged with fluid at the normalbralierpipe pressure, means operative-upon an increase in brake pipepressure above normal for overcharging said reservoir above normal,valve mechanism subjectV to the pressure of fluid from the overchargedreservoir for controlling the release of fluid under pressure from thebrake cylinder, and a reduction chamber,

said means being operative upon eecting a reduction in brake pipepressure a prede termined amount below normal for venting fluid underpressure from said reservoir to said chamber-and operative uponanincrease in brake pipe vpressure for recharging said reservoir. y v

16. In a fluid pressure brake, the combination with a brake pipe and abrake cylinder, of a reservoir normally charged with fluid at the normalbrake pipe pressure, means operative upon an increase in brake pipepressure above normal for overcharging said reservoir above normal,valve mechanism subject to the pressure of fluid from theV overchargedreservoir for controlling the release of fluid under pressure from thebrake cylinder, and a reduction chamber, said means being operative uponeffecting a reduction in brake pipeYV pressure apredetermined amountbelow normal for venting fluid under pressure from said reservoir fia tosaid chamber and operative upon an in-v crease in brake pipe pressurefor recharging said reservoir and for venting fluid from said chamber. YY

17, In a fluid pressure brake, the combination with a brake pipe and abrake cylinder, of an auxiliary reservoir and a controlreservoirnormally charged with fluid Linder pressure through a passage common toboth reservoirs, a valve mechanism subject to the opposing pressuresof'both of said reservoirs for controlling the pressure of fluid in thebrake cylinder, and means operated upon kan over reduction in brake pipepressure for venting fluid under pressure from said con- `trol reservoirindependently of said passage and auxiliary reservoir. Y

Y 1S.r In a fluid pressure` brake, the combination with a brake pipe,arbrake cylinder, an auxiliary reservoir and a control reservoir, of atriple valve device subject tobrake pipe pressure for establishingcommunication through whichfiuid under pressure is supplied to both ofsaid reservoirs and for establishing another communication through whichfluid under pressure is adapted to be said reservoirs for controllingthe release of fluid under pressure fromthe brakey cylinder, said triplevalve device being operative upon a reduction in brake pipe pressure forclosing both of said communications and for establishing acommunicationy through Vwhich fluid under pressure is supplied from.which fluid under pressure 'is adapted to be released from the brakecylinder, a valve device subject'to the opposing pressures of saidreservoirs for controlling the release of fluid under pressure from thebrake cylinder, said triple valve device being operative upon areduction in brake pipe pressure for closing both of' saidcommunications and for establishing a communication through which fluidunder pressure is supplied from the auxiliary reservoir to said brakecylinder, a reduction chamber and means operated upon an over reductionin brake pipe pressure forV venting fluid under pressure from saidcontrol-reservoir to said chamber.

20. In a fluid pressure brake, the combination with a brake ypipe and abrake cylinder, of anormally charged reservoir, valve means subject tothe pressure of fluid from said reservoir forretaining a predeterminedpressure Vin the brakeV cylinder when the brakes are released incycling, a reduction chamber, and means operated upon an over reductionin brake pipepressure for venting fluid under pressure fromsaidreservoir to said chamber to render said valve means ineffective toVretain said predetermined pressure in the brake cylinder. Y

In testimony whereof I vhave hereunto setV my hand, this 26th dayofiDecembenrlQQQ.

CLYDE'C. FARMER.

released from the brakeA cylinder, a valve l f. device` subject totheopposing pressures` of

